This invention relates to automotive air condititioning systems and, more particularly, to an electrically operated expansion valve for use in such a system.
Automotive air conditioning systems typically utilize either a thermostatic expansion valve or an orifice tube to control the flow of refrigerant to the evaporator. While such systems operate generally satisfactorily, the amount of control thereover is minimal. It is therefore a primary object of the present invention to provide an automotive air conditioning system subject to precise control of refrigerant feed to the evaporator.
Automotive control systems are becoming increasingly more sophisticated, with onboard microcomputers being provided for controlling such functions as engine speed, fuel flow, fuel mixture, transmission ratio, etc. It is therefore another object of this invention to provide a means whereby the onboard computer in an automobile may effect precise control over the air conditioning system.
Electrically operated expansion valves are known. However, in an automotive application, where the valve is required to open under a differential pressure of at least 300 p.s.i., the valve operator must be sufficient to open the valve under such differential pressure conditions without placing an undue load upon the automotive electrical system. It is therefore a further object of this invention to provide such an electrically operated valve.